
import pandas as pd
df = pd.DataFrame({'商品':['苹果','香蕉','梨'],'单位':[5,5,4],'销量':[100,None,None],'库存':[50,None,70]})
print('原始数据:\n',df)
print('检查缺失值:\n',df.isnull())
print('检查非缺失值:\n',df.notnull())
print('统计每列缺失值的个数值:\n',df.isnull().sum())